Image acquisition devices having image sensors and implementing an electronic shutter is commonly used, in particular when it comes to capturing motion images, i.e. video sequences. Many of these image acquisition devices also implements a rolling shutter, i.e. the exposure timing for the image sensor varies from row to row in the image sensor. Imagery from these cameras includes a stripe pattern, sometimes only one stripe, in the direction of the rows, which most of the time moves over the motion image. The stripe pattern is an annoying effect and may even be critical in monitoring or surveillance applications as this distinct pattern may make a person watching the motion image lose focus due to its invasive nature. The stripe pattern effect is called flicker and is attributed to the blinking period of light sources lighting the scene captured, e.g. fluorescent lamps, LED lighting, etc., the use of electronic shutter in the image acquisition device.
The problem of flicker in captured images is addressed in U.S. Pat. No. 8,218,029. In this patent, the flicker is removed by means of first generate a reference video signal containing no flicker. Then, the reference video signal is compared with a video signal containing the flicker. Subsequently, based on the comparison, a flicker component showing the characteristic of the flicker contained in the image taking video signal is found. From the flicker component, the characteristic of the flickers contained in the image taking video signal can be recognized and the flickers contained in the image taking video signal can thus be removed (or reduced).